A new study finds that mothers with a high body mass index (BMI) before or during early pregnancy are at greater risk for miscarriage, stillbirth or infant death. The study, published in the Journal of the American Medical Association (JAMA), also found that women who were severely obese had the greatest risk of these outcomes.
According to a JAMA news release, approximately 2.7 million stillbirths occurred in worldwide. In addition, an estimated 3.6 million neonatal deaths – death following a live birth but before the infant is 28 days old – occur each year.
To determine the association between maternal BMI before and during pregnancy and the risk of stillbirth, fetal death and infant death, Dagfinn Aune of the department of epidemiology and biostatistics, the School of Public Health at Imperial College London in England, and his colleagues analyzed data from 38 studies. These studies included more than 10,000 miscarriages, more than 16,200 still births and more than 4,300 deaths near the time of birth.
Aune and his colleagues found that even modest increases in maternal BMI were associated with an increased risk of infant death before birth or shortly after. Women of normal weight had about 76 stillbirths per 10,000 pregnancies compared to 102 stillbirths among women with a BMI of 30. The greatest risk was associated with severely obese women whose BMI of 40 put them at a two- to three-fold greater risk for these outcomes than women who had a BMI of 20.
The investigative team suggested several biological mechanisms associated with excess weight that might put the fetus and child at risk, including high blood pressure and gestational diabetes. The authors called for “further studies…to investigate the mechanisms involved,” and urged women who are planning pregnancies to try to maintain a healthy weight.
“The main message of the study is that maternal overweight and obesity increase the risk of fetal death, stillbirth and infant death,” said Aune. “Since excess weight is a potentially modifiable risk factor, further studies should assess whether lifestyle and weight changes modify the risk of fetal and infant death,” he told Reuters Health in an email.